1. Field of the Invention
The invention concerns a respirator and more particularly a respirator in which flow and pressure of the respiration gas are automatically regulated during inspiration and expiration.
2. Description of the Prior Art
Respirators serve to replace or assist the respiratory funciton in patients having deficient or insufficient spontaneous respiration. Further, respirators can be employed for anaesthesia.
The usual respirators are controlled systems, that is their functional operating sequence is governed by predefined input variables. A group of known respirators, encompasses the so-called pressure-controlled systems, wherein respiration gas under pressure is supplied to the patient, with a control valve interrupting the respiration gas supply if a certain predetermined pressure is built up in the line leading to the patient. A further group encompasses the so-called volume-controlled systems, by which a quantity of the respiration gas measured according to volume is supplied to the patient. Both types of respirators have a disadvantage which is fundamentally inherent to all controlled systems; specifically, they can not respond in a compensating manner to variations of the lung mechanics which cannot be predicted.
There have also already been proposed automatically regulated respirators, which are not suitable "however" for various reasons for general, routine-type use in hospitals. One reason is that the measurement of the controlled condition calls for a complicated mechanism which on the one hand is expensive and on the other hand is trouble-prone.